The Montreal Protocol for the protection of the ozone layer mandated the phase out of the use of chlorofluorocarbons (CFCs). Materials more “friendly” to the ozone layer, such as hydrofluorocarbons (HFCs) eg HFC-134a replaced chlorofluorocarbons. The latter compounds have proven to be green house gases, causing global warming and were regulated by the Kyoto Protocol on Climate Change. The emerging replacement materials, hydrofluoropropenes, were shown to be environmentally acceptable i.e. has zero ozone depletion potential (ODP) and acceptable low global warming potential (GWP).
Currently used blowing agents for thermoset forms include HFC-134a, HFC-245fa, HFC-365mfc that have relatively high global warming potential, and hydrocarbons such as pentane isomers which are flammable and have low energy efficiency. Therefore, new alternative blowing agents are being sought. Halogenated hydroolefinic materials such as hydrofluoropropenes and/or hydrochlorofluoropropenes have generated interest as replacements for HFCs. The inherent chemical instability of these materials in the lower atmosphere provides for a low global warming potential and zero or near zero ozone depletion properties desired.
US 2009/0099272 A1 disclosed, “A shortcoming of two-component systems, especially those using certain hydrohaloolefins, including, HFO-1234ze and HFCO-1233zd is the shelf-life of the B-side composition. Normally when a foam is produced by bringing together the A and B component, a good foam is obtained. However, if the polyol premix composition is aged, prior to treatment with the polyisocyanate, the foam are of lower quality and may even collapse during the formation of foam”.